The present invention relates to a method of manufacture of an organic electroluminescence display device using organic electroluminescence, and, more particularly, the invention relates to an image forming method in which a polymer light emitting material solution is held and formed at given pixel center portions while making the formation of partition walls (banks) which define the pixels unnecessary.
An organic electroluminescence device, which utilizes mainly an organic material as field light emitting elements, is suitable for an application as a planar display; and, hence, an extensive development has been under way and the remarkable progress has been made in fields such as materials, element structures, fabrication techniques for light emission.
To constitute a highly reliable planar display device using organic electroluminescent elements of this type, it is necessary to accurately arrange light emitting elements using an organic material having a light emitting property of high efficiency on a pixel area portion of an insulation substrate made of glass or the like to serve as organic electroluminescence elements. In addition to the above-mentioned arrangement, to provide a display device of high quality and high reliability in which the light emitting efficiency and the light emitting luminance are enhanced for a long period in a stable manner over a long lifetime, a technique to properly form pixels constituted of organic electroluminescent elements on an insulation substrate becomes crucially important. Here, some tasks which are required for the formation of the pixels are versatile, as described below.
Conventionally, with the development of a technique for putting the planar display device using organic electroluminescence elements of this type into practice, in a polymer-based organic electroluminescent element which forms a light emitting material film using an ink jet method, to hold an organic material solution (ink) in the inside of the pixels while preventing a flowing out of the organic material solution to neighboring pixels, it has been proposed to form banks, which define respective pixels, and, thereafter, to form a hole injection layer and a light emitting layer.
As an example, the following “patent literature 1” discloses a structure which can realize a full color display, wherein, by forming banks, organic light emitting layers having respective light emitting colors of red, green and blue can be arbitrarily patterned for every pixel by forming and arranging organic electroluminescence materials whose patterning was considered impossible conventionally using an ink jet method.
Further, the following “patent literature 2” discloses a structure which can realize a vivid color display, wherein by using a bank material which is water-repellant and oil-repellant with respect to various inks, it is possible to prevent color mixing of inks between pixels which may occur due to bridging over of a material having a hole injection layer and a light emitting layer between the pixels, thus making fluorescent materials in use emit lights of colors of the fluorescent materials faithfully.
Further, the following “patent literature 3” discloses a structure which can prevent thin-film-forming-material ink from flowing out to neighboring pixels and, at the same time, can obtain a uniform film thickness by forming banks, such that a material which exhibits affinity with the ink and a material which exhibits non-affinity with ink are alternately stacked. Here, the non-affinity with the ink is given to the banks by applying a fluorine plasma treatment to the banks.
Further, the following “patent literature 4” discloses a method in which, in the manufacture of color filters, energy rays are irradiated to pixel portions on a substrate to make the pixel portions have an affinity with ink, thus reducing the occurrence of defects attributed to a repelling of the ink.
Further, the following “patent literature 5” discloses a manufacturing method of manufacture of an organic electroluminescence element in which ultraviolet rays are irradiated to upper surfaces of anodes so as to improve the adhesiveness with an organic material (a hole injection layer) formed on the upper surfaces of the anodes.
The patent literatures referred to above are identified as follows.
[Patent Literature 1]
Japanese Unexamined Patent Publication Hei10 (JP-A-1998)-12377
[Patent Literature 2]
Japanese Unexamined Patent Publication Hei11 (JP-A-1999)-87062
[Patent Literature 3]
Japanese Unexamined Patent Publication Hei11 (JP-A-1999)-271753, and its counterpart U.S. Pat. No. 6,476,988.
[Patent Literature 4]
Japanese Unexamined Patent Publication Hei9 (JP-A-1997)-230129
[Patent Literature 5]
Japanese Unexamined Patent Publication Hei10 (JP-A-1998)-261484, and its counterpart U.S. Pat. No. 6,060,826.